There are no laws about dating.
It is illegal to engage in sexual activity with someone under the age of 16.
Yes, its illegal in fact.
No. It is illegal. The minor child can not sleep with an unrelated 19 year old adult.
It is not illegal, but it is a bad idea. The 19 year old could ruin their life if there is even a hint at sexual contact. There is much too much of an age difference.
No. A 12 year old is a minor teen and below the age of consent in all states. It is illegal for an adult of 19 to date a minor and this is considered child sexual abuse. A 19 year old who would date a 12 year old has a problem and would only one thing from a girl of 12.
It is not illegal but it is unusual
It is legal, but in most places it will be illegal to have intercourse with this person. So be careful, because they will eventually want to go further with you.
No
It depends on where you are. Few places have legislation prohibiting dating. It may not be illegal to date but a 12 year old is a minor and below the age of consent for sexual contact. The 19 year old would be very stupid to date someone that young, it could land them in jail if the younger one accuses them of doing something, whether they actually did or not.
That depends on where you live.
No
No, that would be illegal.
Its not illegal to be 'dating' and 15 year old if your 19. But if you so much as kiss her you can be considered a sex offender for the rest of your life.